LPG vaporizer

ABSTRACT

An LPG vaporizer has an elongated upright pressure vessel substantially surrounded by a water jacket. There are upright flues around the pressure vessel and extending through the water jacket from a combustion chamber below the pressure vessel to a flue chamber above the pressure vessel. Parallel thermo-syphon tubes are disposed in the pressure vessel and open at their bottom and top into the water jacket. LPG liquid is supplied to the pressure vessel under float control and LPG gas is discharged from the pressure vessel, some being diverted for use in a burner in the combustion chamber.

United States Patent [1 1 Jerde 1 1 LPG VAPORIZER [75] Inventor: James B. Jerde, San Leandro, Califv [73] Assignee: Ransome Gas Industries, Inc.. San

Leandro, Calif.

[22] Filed: Oct. 16, 1974 [21] Appl. No.: 515,326

[52] 11.8. C1. 122/156; 62/52; 122/33; 122/367 C; 122/448 R; 122/451 R [51] Int. Cl. F2213 7/00; F22B 35/00 [58] Field of Search 122/33, 156, 367 R, 367 C, 122/448 R, 451 R; 62/52 [56] References Cited UNITED STATES PATENTS 2,561,506 7/1951 Garretson 122/33 X 3.106956 10/1963 Smith et al..... 62/52 X 3.151439 10/1964 Golden 62/52 [451 Aug. s, 1975 Sullivan 62/52 Arenson 62/52 Primary Eranzinerl(enneth W. Sprague Attorney, Agent, or FirmL0throp & West [57] ABSTRACT An LPG vaporizer has an elongated upright pressure vessel substantially surrounded by a water jacket. There are upright flues around the pressure vessel and extending through the water jacket from a combustion chamber below the pressure vessel to a flue chamber above the pressure vessel. Parallel thermo-syphon tubes are disposed in the pressure vessel and open at their bottom and top into the water jacket. LPG liquid is supplied to the pressure vessel under float control and LPG gas is discharged from the pressure vessel. some being diverted for use in a burner in the combustion chamber.

4 Claims, 3 Drawing Figures SHEET PATENTED AUB 51975 LPG VAPORIZER The use of LPG gas is now widespread, the gas being a hydrocarbon or hydrocarbon combination which customarily is stored or reserved in liquid form and which is heated into vapor or gas form for utilization, some of the LPG gas itself being utilized as a fuel for heating ad ditional, liquid LPG. There is a requirement for a relatively small, unitized vaporizer which can be used in multiples, if desired, and which will operate safely and consistently despite variant weather conditions, and which will also supply substantial amounts of vapor, even overload amounts for a short time, during the operation of the mechanism. In some installations there are sometimes deposits in the exhaust mechanism of the vaporizer of materials which are highly deleterious to long-term operation, and even in the gas circuitry there are sometimes deposits that are objectionable.

It is therefore an object of the invention to provide an LPG vaporizer which will satisfy the requirement for unitary construction and substantial temporary overcapacity and which will in general be safe, long-lived and economical to build, service and operate.

It is also an object of the invention to provide an LPG vaporizer which can function satisfactorily in various kinds of weather and with little or no deleterious deposits either in the exhaust system or in the internal circulating system.

It is a further object of the invention in general to provide an economically constructed, safe and versatile LPG vaporizer.

Other objects, together with the foregoing, are attained in the embodiment of the invention described in the accompanying description and illustrated in the accompanying drawings, in which:

FIG. 1 is partly diagrammatic and partly a crosssection on a vertical axial plane through a form of LPG vaporizer constructed pursuant to the invention;

FIG. 2 is a crosssection, the plane of which is indicated by the line 22 of FIG. 1', and

FIG. 3 is a diagram showing one form of control in strumentality used with and in the vaporizer.

The vaporizer of the invention can be embodied in a widely variant number of forms, all retaining the desir able principles, but it has with commercial success been incorporated as a unit for single or multiple installation as shown herein. The present arrangement employs a pressure vessel 6 preferably of circularcylindrical configuration symmetrical or substantially so about an axis 7 that is preferably arranged upright so that the vessel 6 is substantially vertical. Conveniently, the vessel 6 is fabricated of a circularcylindrical central section 8 closed at its lower end by a lower head 9 and closed at its upper end by an upper head 11, so that the resulting vessel can sustain considerable internal pressure.

Surrounding or nearly surrounding the pressure vessel 6 is a water jacket 12 also conveniently of circularcylindrical configuration standing upright and coaxially with the pressure vessel and inclusive not only of an outer wall but also of a lower header plate 13 and an upper header plate 14. The water jacket is augmented by a plurality of thermo-syphon tubes 16, 17 and 18, each of which has an upright section 19 extending within the pressure vessel parallel to the axis 7 and having a lower end elbow 2] opening into the bottom part of the waterjacket and also having an upper elbow 22 opening into the upper portion of the water jacket.

Near the upper end of the water jacket is a water filler tube 26 with a removable filler cap 27. A gage glass 25 is titted at the customary level range. At the lower end the water jacket is provided with a normally plugged drain fitting 28. There is thus afforded an enclosed body of water substantially surrounding the major portion of the pressure vessel and augmented with thermosyphon tubes so that there is a large surface for heat interchange between the interior of the pressure vessel and the water jacket, and so that there is beneficial water circulation for better heat transfer and favorable temperature conditions.

Beneath the lower header plate 13 the sides of the water jacket 12 extend downwardly to form a partial enclosure for a burner mechanism 31. When operating, the burner supplies hot gas through various tubular flues 32 to an upper flue chamber 33 disposed within the extended walls of the water jacket above the upper end of the pressure vessel. The flues 32 are numerous and are arranged with their own axes parallel to the axis 7 and are disposed substantially all the way around the pressure vessel. Exhaust or spent flue gas from the chamber 33 is released through a vent duct 34 having a dissipating cap 36 of any convenient kind. The mechanism is conveniently housed within an enclosing cabinet 37 to protect against the weather and to conserve heat.

As an additional means for heat transfer between the waterjacket and the pressure vessel there are provided fins 41 secured to and extending radially outwardly from the walls of the pressure vessel into the surrounding water jacket, the fins being interspersed between the flues 32. For convenience in construction and other reasons, the fins are of a vertical height substantially less than that of the pressure vessel and in practice extend primarily between the lower elbow 21 and the upper elbow 22 of the various thermo-syphon tubes.

As part of the operational and controlling mechanism useful with the structure so far described, there is preferably afforded a pipe 46 connected to a supply of LPG liquid under pressure and received through a strainer or filter 47 in a supply line 48. There is a control valve 49 for governing the flow of such liquid from the pipe 48 into a duct 51 connected to a line 52 ending in a pipe 53 opening into the interior of the pressure vessel 6. Conveniently there is a check valve shunt line 54 around the valve 49 and inclusive of a check valve 56 therein. This permits back flow should pressure in the pressure vessel 6 become excessive.

To secure operation of the liquid control valve 49, there is a pilot valve 6i, especially illustrated in detail in FIG. 3. In a fitting 62 opening to the inside of the pressure vessel 6, there is a seat 63 cooperating with a poppet disk 64 at the end of an actuating stem 66. A spring 67 normally urges the poppet 64 closed. A float ball 68 within the pressure vessel at an appropriate level rests upon the stem 66 or, if the stem happens to be removed for service, rests alternatively in its lower most position upon a cross rod 69 projecting from the wall of the vessel 6. When there is sufficient liquid in the vessel to buoy the ball 68 above the stem 66, the spring 67 retains the valve 64 closed, but when the liquid level falls and the ball float 68 descends by gravity, it rests upon the rod 69 and cocks or slants the rod so that the poppet 64 is rocked from its seat against the urgency of the spring 67 and is thus opened. Consequently, the valve is opened and closed in accordance with liquid level within the pressure vessel.

Within the control valve 49 the liquid inlet pipe 48 terminates in a seat 71 on which a valve 72 may rest or from which the valve 72 may be displaced. The valve itself is in a flexible diaphragm 73 peripherally clamped within the housing of the valve 49. There is a small pas sageway 74 through the valve member 72 and there is a duct 76 leading from the valve interior just above the diaphragm 73 to the fitting 62.

In operation, there is normally liquid pressure in the pipe 48 against the valve 72 and that pressure is sufficient to lift that valve so that the liquid can flow out through the pipe 51 and the connector 52 and the fitting 53 to fill the deficient pressure vessel 6. At the same time, there is some leakage of the incoming liquid through the duct 74 and through the duct 76 to flow in through the then-open valve 64, because the level is low enough so that the valve disk 64 is cocked off its seat by the weight of the float ball 68. When the liquid level rises sufficiently within the pressure vessel 6, the float 68 lifts, and the valve disk 64 closes. Liquid flowing through the passage 74 fills and pressurizes the space above the diaphragm 73, so that the valve 72 tends to close. When the valve is nearly closed, it is urged firmly onto its seat since the total pressure in the duct 48 communicated through the passageway 74 to the upper area of the diaphragm 73 is greater than the total pressure from below. There is a firm shutoff of the incoming liquid. When the liquid level eventually falls and the valve 72 is again opened under initial conditions, the pressure above the diaphragm 73 drops and the pressure beneath the valve 72 opens it. This condition obtains until the liquid level rises again when the ball 68 in lifting permits the valve 64 to close again. The cycle repeats itself, thus maintaining substantially a set or predetermined liquid level or level range within the vaporizer pressure vessel 6.

Vapor derived from the liquid within the pressure vessel is collected beneath the upper end 11 thereof and flows outwardly from the pressure vessel through fittings 81 and a pipe 82 to a cross unit 83. One of the branches 84 of the unit 83 is to a relief valve (not shown) to the atmosphere or waste so that any excessive pressure can be let go. Another branch 86 from the cross unit 83 is to the remote burner or burners supplied by this vaporizer unit. Another branch 87 of the valve 83 takes a portion of the generated gas and leads it through a shutoff valve 88 and through a line 89 and a pair of pressure regulators 91 and 92 to supply a line 93 leading through a thermal control valve 94 and a pipe 96 to the burner 31. Thus the gas supplied to the burner 31 is utilized to afford additional vaporization of LPG.

In order to actuate the temperature valve or thermal valve 94, there is mounted through the water jacket 12 a thermally responsive element 97 preferably disposed in the water jacket immediately opposite the outlet of an upper elbow 22 at the upper end of a thermosyphon tube. The thermally responsive element 97 has a connection 98 for opening and closing the valve 94 in accordance with water temperature. This temperature is normally set so that the water in the water jacket is maintained substantially below its local boiling temperature, but, if desired, a liquid other than water or in addition to water may be utilized in the water jacket and a different temperature setting employed.

i During the normal operation of this arrangement, the water in the water jacket is heated primarily from below and adjacent the flues 32. it gradually increases in temperature and tends to rise. As this occurs, water within the thermosyphon tubes 16 tends to circulate downwardly on the inside of the pressure vessel and tends to return at the bottom elbows to the waterjacket outside of the pressure vessel for reheating, having given up some of its heat to the contents of the pressure vessel. In this way there is maintained an accurate and vigorous water circulation within the otherwise relatively static body of water in the water jacket. Discounting the few degrees in temperature difference necessary to maintain the thermo-syphon circulation, it is generally true that the temperature of the water within the water jacket is maintained relatively uniform. The vaporization within the pressure vessel consequently takes place uniformly therein and especially at a carefully controlled and well maintained temperature.

An exception is in the event there should be an extraordinary demand for vapor from the vaporizer. In this event additional incoming liquid is vaporized not only by reason ofthe heat derived instantaneously from the burner 31, but also from heat which has previously been derived therefrom and is currently stored in the surrounding jacket water. This operation of overcapac ity gas supply is productive ofa lowering of water temperature and cannot be continued indefinitely, but is a valuable adjunct in supplying sudden overload surges.

The normally even temperature of the gas conversion is effective to reduce unwanted deposits in the flue system, which sometimes occur when there are wide varia tions in vaporizing temperature, and the same uniform temperature characteristic is also helpful in reducing deposits within the control valves 83, 88, 91, 92 and 94. The net result of the use of a vaporizer as described is to provide a compact unit which can be used in multiple and which is safe, substantially free of service requirements and is efficiently effective.

What is claimed is:

1. An LPG vaporizer comprising an elongated pres sure vessel generally symmetrical about an upright axis, a water jacket substantially surrounding said pressure vessel, means forming upright flues extending through said water jacket and arrayed around said pressure vessel, a combustion chamber adjacent the lower end of said pressure vessel and opening to said flues, means in said combustion chamber for burning fuel, a flue chamber adjacent the upper end of said pressure vessel and opening to said flues, thermo-syphon tubes parallel to said axis extending at least partially through said pressure vessel and open at the upper and lower ends thereof to said water jacket, an LPG inlet to said pressure vessel. and an LPG outlet from said pressure vessel.

2. A vaporizer as in claim 1 including thermal fins on said pressure vessel extending into said water jacket.

3. A vaporizer as in claim 1 including a first flow control valve in said LPG inlet, a float in said pressure ves sel above said thermo-syphon tubes, and means for operating said first flow control valve in response to the position of said float.

4. A vaporizer as in claim I including a second control valve for said fuel burning means, and a temperature-responsive device in said water jacket adjacent the upper end of one of said thermo-syphon tubes for operating said second control valve. 

1. An LPG vaporizer comprising an elongated pressure vessel generally symmetrical about an upright axis, a water jacket substantially surrounding said pressure vessel, means forming upright flues extending through said water jacket and arrayed around said pressure vessel, a combustion chamber adjacent the lower end of said pressure vessel and opening to said flues, means in said combustion chamber for burning fuel, a flue chamber adjacent the upper end of said pressure vessel and opening to said flues, thermo-syphon tubes parallel to said axis extending at least partially through said pressure vessel and open at the upper and lower ends thereof to said water jacket, an LPG inlet to said pressure vessel, and an LPG outlet from said pressure vessel.
 2. A vaporizer as in claim 1 including thermal fins on said pressure vessel extending into said water jacket.
 3. A vaporizer as in claim 1 including a first flow control valve in said LPG inlet, a float in said pressure vessel above said thermo-syphon tubes, and means for operating said first flow control valve in response to the position of said float.
 4. A vaporizer as in claim 1 including a second control valve for said fuel burning means, and a temperature-responsive device in said water jacket adjacent the upper end of one of said thermo-syphon tubes for operating said second control valve. 